| 1. |
- Fischer, Peter M., et al.
(författare)
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A 6000-year record of climate change from Hala Sultan Tekke, Cyprus
- 2023
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Ingår i: The Decline of Bronze Age Civilisations in the Mediterranean: Cyprus and Beyond, 17-18 Januari, 2020, Gothenburg Sweden / edited by Theresa Bürge & Peter Fischer. - Nicosia : Astrom Editions. - 0081-8232. - 9789925793532
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Konferensbidrag (refereegranskat)abstract
- Our study suggests that the history of civilisations in the Eastern Mediterranean has been partially affected by climate by contributing to social unrest and migration. Five important cold periods have been identified in the Hala Sultan Tekke palaeoclimate reconstruction at 5250±20, 4215±40, 3200±90, 1400±70 and 620±20 years BP. Each cold period is consistent with a significant instability in precipitation, mainly for winter and spring seasons. The 3.2ka BP event is not an isolated event and is part of the 1000-year cycles between the main cold and dry episodes at 5200, 4200 and 3200 BP. When occurring coevally, climate and socio-economic factors were probably important drivers of major crises, which appears to have been the case at Hala Sultan Tekke during the final period of the Late Bronze Age.
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| 2. |
- Githumbi, Esther, et al.
(författare)
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European pollen-based REVEALS land-cover reconstructions for the Holocene : Methodology, mapping and potentials
- 2022
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Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 14:4, s. 1581-1619
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative reconstructions of past land cover are necessary to determine the processes involved in climate-human-land-cover interactions. We present the first temporally continuous and most spatially extensive pollen-based land-cover reconstruction for Europe over the Holocene (last 11g€¯700g€¯calg€¯yrg€¯BP). We describe how vegetation cover has been quantified from pollen records at a 11 spatial scale using the "Regional Estimates of VEgetation Abundance from Large Sites"(REVEALS) model. REVEALS calculates estimates of past regional vegetation cover in proportions or percentages. REVEALS has been applied to 1128 pollen records across Europe and part of the eastern Mediterranean-Black Sea-Caspian corridor (30-75° N, 25° W-50° E) to reconstruct the percentage cover of 31 plant taxa assigned to 12 plant functional types (PFTs) and 3 land-cover types (LCTs). A new synthesis of relative pollen productivities (RPPs) for European plant taxa was performed for this reconstruction. It includes multiple RPP values (≥2 values) for 39 taxa and single values for 15 taxa (total of 54 taxa). To illustrate this, we present distribution maps for five taxa (Calluna vulgaris, Cerealia type (t)., Picea abies, deciduous Quercus t. and evergreen Quercus t.) and three land-cover types (open land, OL; evergreen trees, ETs; and summer-green trees, STs) for eight selected time windows. The reliability of the REVEALS reconstructions and issues related to the interpretation of the results in terms of landscape openness and human-induced vegetation change are discussed. This is followed by a review of the current use of this reconstruction and its future potential utility and development. REVEALS data quality are primarily determined by pollen count data (pollen count and sample, pollen identification, and chronology) and site type and number (lake or bog, large or small, one site vs. multiple sites) used for REVEALS analysis (for each grid cell). A large number of sites with high-quality pollen count data will produce more reliable land-cover estimates with lower standard errors compared to a low number of sites with lower-quality pollen count data. The REVEALS data presented here can be downloaded from https://doi.org/10.1594/PANGAEA.937075 (Fyfe et al., 2022).
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| 3. |
- Goni, Maria Fernanda Sanchez, et al.
(författare)
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The ACER pollen and charcoal database : a global resource to document vegetation and fire response to abrupt climate changes during the last glacial period
- 2017
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Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 9:2, s. 679-695
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Tidskriftsartikel (refereegranskat)abstract
- Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st-century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard-Oeschger (D-O) cycles during the last glacial period, which were sufficiently large to have had a potential feedback through changes in albedo and greenhouse gas emissions on climate. Previous reconstructions of vegetation and fire changes during the D-O cycles used independently constructed age models, making it difficult to compare the changes between different sites and regions. Here, we present the ACER (Abrupt Climate Changes and Environmental Responses) global database, which includes 93 pollen records from the last glacial period (73-15 ka) with a temporal resolution better than 1000 years, 32 of which also provide charcoal records. A harmonized and consistent chronology based on radiometric dating (C-14, U-234/Th-230, optically stimulated luminescence (OSL), Ar-40/Ar-39-dated tephra layers) has been constructed for 86 of these records, although in some cases additional information was derived using common control points based on event stratigraphy. The ACER database compiles metadata including geospatial and dating information, pollen and charcoal counts, and pollen percentages of the characteristic biomes and is archived in Microsoft Access (TM) at https://doi. org/10.1594/PANGAEA. 870867.
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| 4. |
- Kaniewski, David, et al.
(författare)
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Climate Change and Social Unrest: A 6,000‐Year Chronicle From the Eastern Mediterranean
- 2020
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Ingår i: Geophysical Research Letters. - 0094-8276. ; 47:7
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Tidskriftsartikel (refereegranskat)abstract
- The history of the Eastern Mediterranean is punctuated by major crises that have influenced many of the region's established socioeconomic models. Recent studies have underscored the role of drought and temperature oscillations in driving changes but attempts to quantify their magnitude remain equivocal, hindering long‐term assessments of the potential interplay between climate and society. Here, we fill this knowledge gap using a 6,000‐year pollen‐based reconstruction of temperature and precipitation from Hala Sultan Tekke, Cyprus. We find that major social changes and plague outbreaks often occurred in tandem with cooler climate conditions, with anomalies ranging from −3 ± 0.4 °C to −1 ± 0.5 °C, coupled with changing precipitation patterns. We suggest that major climate changes may weaken societies by affecting primary livelihood systems. This long‐term view highlights recurrent cold periods in the Eastern Mediterranean's climate history and advocates that, despite frequent adversity and pandemics, Near Eastern populations adapted and were ultimately resilient to major climate changes.
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| 5. |
- Lehsten, Dörte, et al.
(författare)
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Modelling the Holocene migrational dynamics of Fagus sylvatica L. and Picea abies (L.) H. Karst
- 2014
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-8238 .- 1466-822X. ; 23:6, s. 658-668
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Tidskriftsartikel (refereegranskat)abstract
- Aim Vegetation dynamics and the competitive interactions involved are assumed to restrict the ability of species to migrate. But in most migration modelling approaches disturbance-driven succession and competition processes are reduced to simple assumptions or are even missing. The aim of this study was to test a combination of a migration model and a dynamic vegetation model to estimate the migration of tree species controlled by climate, environment and local species dynamics such as succession and competition. Location Europe. Methods To estimate the effect of vegetation dynamics on the migration of European beech and Norway spruce, we developed a post-process migration tool (LPJ-CATS). This tool integrates outputs of the migration model CATS and the dynamic vegetation model LPJ-GUESS. The model LPJ-CATS relies on a linear dependency between the dispersal kernel and migration rate and is based on the assumption that competition reduces fecundity. Results Simulating potential migration rates with the CATS model, which does not account for competition and disturbance, resulted in mean Holocene migration rates of 435 +/- 55 and 330 +/- 95 m year(-1) for the two species Picea abies and Fagus sylvatica, respectively. With LPJ-CATS, these mean migration rates were reduced to 250 +/- 75 and 170 +/- 60 m year(-1) for spruce and beech, respectively. Moreover, LPJ-CATS simulated migration pathways of these two species that generally comply well with those documented in the palaeo-records. Main conclusions Our 'hybrid' modelling approach allowed for the simulation of generally realistic Holocene migration rates and pathways of the two study species on a continental scale. It suggests that competition can considerably modify spread rates, but also the magnitude of its effect depends on how close climate conditions are to the niche requirements of a particular species.
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